My mercury monterey 2004 was involved in accident in September 2010. We got the van back from dealership and our van was shutting itself off when idled and shaking when going over 40 miles per hour and when stepping on gas pedal. We took van back to dealership and we just got it back in January 2011. Now, it is shaking when stepping on gas pedal, going uphill and when going over 40 miles per hour along with making a loud changing gear sound, no smell noticed, and the check engine light came on today 3/23/11. Do you know what the problem may be?